Experts often refer to magnesium as a hidden hero of nutrition. This essential mineral helps the body produce energy, regulate blood sugar and blood pressure, and support nerve and muscle function—including that of the heart, according to the National Institutes of Health (NIH). Recognising the signs of magnesium deficiency may help identify when intake falls short.
“Magnesium is one of those under-the-radar minerals that quietly powers hundreds of essential processes in the body,” says accredited practising dietitian Samantha Peterson.
Although true deficiency is uncommon, studies suggest that almost half of people fall short on magnesium intake. This is often due to diets low in magnesium-rich whole foods like vegetables, says director of product innovation and scientific affairs Erin Barrett. Processing also strips minerals from many packaged foods.
Some individuals may have higher needs or difficulty absorbing magnesium. This includes older adults and those with certain health conditions such as gastrointestinal disorders, type 2 diabetes or substance use challenges, explains nutrition consultant Amy Davis.
Because symptoms of magnesium deficiency are not always obvious, many people may not realise they’re running low. However, there are some subtle—and not-so-subtle—signs worth noting, according to experts.
Fatigue
Persistent tiredness, weakness or low energy could be a sign the body isn’t making energy effectively. “Magnesium is essential for producing ATP, the body’s main energy molecule,” says Barrett. “Without enough of it, cells can’t generate or use energy efficiently, which may lead to ongoing fatigue or muscle weakness.”
If rest doesn’t improve symptoms, it could point to a deeper issue. “Look out for fatigue that feels persistent and doesn’t improve with sleep or downtime,” adds registered dietitian and nutritionist Matt Landry.
Muscle cramps and spasms
Low magnesium can lead to cramping, twitching, spasms or tingling sensations in the muscles. In more severe cases, it may even contribute to seizures or repetitive eye movements (nystagmus), says Barrett. That’s because magnesium helps regulate calcium and potassium, which both play key roles in nerve and muscle function.
“When magnesium is low, nerves and muscles become more excitable,” Barrett explains. This can make muscles feel weaker, more prone to twitching or simply different from usual. Common signs include waking with tight calves or experiencing night-time leg cramps, adds Peterson.
Anxiety or irritability
If stress, anxiety or irritability seem to appear without a clear trigger, magnesium levels may be worth checking. Magnesium supports the nervous system and helps regulate neurotransmitters involved in mood, including dopamine, serotonin and epinephrine.
“When magnesium is low, the brain and muscles can go into overdrive, leaving you feeling on-edge, tense or overly reactive,” says Peterson. Some people may notice heightened anxiety, while others may feel emotionally overstimulated or more irritable than usual.
Irregular heartbeat
An irregular or racing heartbeat is always worth discussing with a doctor. In some cases, magnesium deficiency may be a contributing factor. “Magnesium plays a role in stabilising the heart’s electrical signals,” says Davis. Low levels can disrupt this balance, potentially causing the heart to beat irregularly or more quickly than usual.
Headaches
Magnesium also plays a role in blood vessel function and nerve signalling in the brain. A deficiency may increase the likelihood of headaches or migraines, especially if they start becoming more frequent.
“Low magnesium levels have been linked to migraine risk in some people,” says Barrett. While this symptom doesn’t affect everyone, it’s one to watch—especially if paired with other signs of low magnesium.
Trouble sleeping
Magnesium affects both energy and rest—so a deficiency may leave someone feeling tired yet unable to sleep properly. “If someone is feeling ‘wired but tired’ or struggling to fall asleep despite exhaustion, I often take a closer look at magnesium,” says Peterson.
In some cases, the mind may race at bedtime or sleep may feel unrefreshing. Barrett adds that disrupted rest, even after sufficient hours in bed, could signal a magnesium shortfall. Always speak with a healthcare professional before making changes to supplements or diet.
High blood pressure
Magnesium helps keep blood pressure within a healthy range by relaxing the blood vessels and supporting proper circulation. When levels are low, the risk of high blood pressure may increase, according to Barrett and Davis.
“Magnesium helps relax blood vessel walls, supporting healthy blood flow and pressure,” says Barrett. Research also suggests that increasing magnesium through diet or supplements may help reduce the risk of cardiovascular issues such as heart disease and stroke.
Mood swings
Irritability, low mood or emotional shifts could all be signs of low magnesium. “Magnesium helps regulate neurotransmitters and the body’s stress response,” explains Davis. When this balance is disrupted, symptoms may include mood swings, mild depression or what Landry refers to as “personality changes.”
Peterson calls magnesium the body’s natural “chill-out mineral,” noting that without enough of it, the nervous system can misfire and affect mood.
Digestion issues
Magnesium also plays a role in digestive function. A deficiency may lead to constipation or irregular bowel movements, says Peterson. While these symptoms can point to many different health concerns, Peterson suggests looking for combinations—such as digestive discomfort alongside chronic stress or muscle cramps.
“A red flag combo?” she says. “Constipation and chronic stress.” If multiple symptoms are present, magnesium levels could be worth investigating with a health professional.
Sugar cravings
Unexpected sugar cravings might not just be about willpower. Low magnesium could be a hidden driver, according to Peterson. The mineral helps regulate blood sugar levels, and a deficiency may make it harder for the body to maintain stable glucose, Barrett explains.
Blood sugar imbalances—such as hypoglycaemia (low blood sugar) or hyperglycaemia (high blood sugar)—can increase hunger and lead to cravings. If sugar is suddenly harder to resist, magnesium levels may be worth checking.
Weak bones
Magnesium supports healthy bone development and density by assisting in the regulation of calcium and vitamin D—two essential nutrients for bone strength, Barrett says.
Over time, insufficient magnesium may lead to a reduction in bone density. Davis and Barrett note that this can raise the risk of developing osteoporosis, a condition in which bones become fragile and prone to fractures.
The bottom line
If a magnesium shortfall is contributing to health concerns, improving dietary intake may ease symptoms, says Landry. Foods rich in magnesium—such as leafy greens, legumes, nuts and seeds—can support daily needs. In some cases, magnesium supplementation may be appropriate, but this should be guided by a healthcare professional.
A blood test can confirm whether magnesium levels are low. From there, a doctor can recommend a safe and personalised approach.
Dietary supplements are products intended to supplement the diet. They are not medicines and are not intended to treat, diagnose, mitigate, prevent, or cure diseases. Be cautious about taking dietary supplements if you are pregnant or nursing. Also, be careful about giving supplements to a child, unless recommended by their healthcare provider.
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